/**
 * Copyright (c) 2005-2011 huisou.com
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * 
 * $Id: SpringContextHolder.java 1468 2011-02-10 15:22:48Z Valiant $
 */
package com.chenzehe.java.core;

import com.chenzehe.java.core.utils.AssertUtils;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.DisposableBean;
import org.springframework.context.ApplicationContext;
import org.springframework.context.ApplicationContextAware;

/**
 * 以静态变量保存Spring ApplicationContext, 可在任何代码任何地方任何时候取出ApplicaitonContext.
 * 
 * @author Valiant
 */
public class SpringContextHolder implements ApplicationContextAware, DisposableBean {
	
	private static ApplicationContext	applicationContext	= null;
	
	private static Logger				logger				= LoggerFactory.getLogger(SpringContextHolder.class);
	
	/**
	 * 取得存储在静态变量中的ApplicationContext.
	 */
	public static ApplicationContext getApplicationContext() {
		assertContextInjected();
		return applicationContext;
	}
	
	/**
	 * 从静态变量applicationContext中取得Bean, 自动转型为所赋值对象的类型.
	 */
	public static <T> T getBean(String name) {
		assertContextInjected();
		return (T) applicationContext.getBean(name);
	}
	
	/**
	 * 从静态变量applicationContext中取得Bean, 自动转型为所赋值对象的类型.
	 */
	public static <T> T getBean(Class<T> requiredType) {
		assertContextInjected();
		return applicationContext.getBean(requiredType);
	}
	
	/**
	 * 清除SpringContextHolder中的ApplicationContext为Null.
	 */
	public static void clearHolder() {
		logger.debug("清除SpringContextHolder中的ApplicationContext:" + applicationContext);
		applicationContext = null;
	}
	
	/**
	 * 实现ApplicationContextAware接口, 注入Context到静态变量中.
	 */
	
	public void setApplicationContext(ApplicationContext applicationContext) {
		logger.debug("注入ApplicationContext到SpringContextHolder:" + applicationContext);
		
		if (SpringContextHolder.applicationContext != null) {
			logger.warn("SpringContextHolder中的ApplicationContext被覆盖, 原有ApplicationContext为:" + SpringContextHolder.applicationContext);
		}
		
		SpringContextHolder.applicationContext = applicationContext; // NOSONAR
	}
	
	/**
	 * 实现DisposableBean接口, 在Context关闭时清理静态变量.
	 */
	
	public void destroy() throws Exception {
		SpringContextHolder.clearHolder();
	}
	
	/**
	 * 检查ApplicationContext不为空.
	 */
	private static void assertContextInjected() {
		AssertUtils.state(applicationContext != null, "applicaitonContext属性未注入, 请在applicationContext.xml中定义SpringContextHolder.");
	}
}
